Resist the urge to put the top on first. Covering the ends first, leaves more surface area of the structure exposed for taping. If you put the top on first, you will only be able to tape the ends over the top instead of around the structural tubing where a more secure binding can be made. However, if you want to be able to remove the end coverings, then you might as well put them on last.
Now that the top and sides of the basic structure are completed, we're going to close up the ends and build the door frame and finally the door itself. I'll build the door 'in place' because the doorframe may not be perfectly square.
Flip through the slide show below to see the process.
This is my greenhouse experiment. The 'high-tunnel' greenhouse design is just about the cheapest to build because it requires very little in the way of materials. This will be a 10' x 24' greenhouse built for around $500 over a few weekends.
The tricky part in this design lies in finding precisely the right size of 3/4" PVC pipe. In this case, it's the inside diameter that we're concerned about. Measure your pipe carefully (before you buy it) and get the stuff that is between 29/32" and 15/16" ID. A lot of it will be 7/8 but skip those because you will not be able to insert the metal conduit. You want the stuff with the widest opening so the metal conduit (aided with a bit of WD-40) will slide in from 6" to 24" giving a lot of wiggle room in the positioning while giving a snug fit. I didn't find any that were too big.
Flip through the gallery below to see part 1 (of 4?) of the construction process - framing the structure.
This was one of my first projects in the kitchen. We had a pantry that had very deep shelves and it was hard to keep it organized because you could only ever see about 1/10th of what was in there. By splitting the space into two sets of shallow shelving and putting one set of shelves in the door, we made the space a lot more usable. We can still pack it full of stuff but now everything is a lot more visible and accessible.